Changing the default icons in OS X is one of the best ways to personalize your mac. And after you have done it once or twice you’ll see how easy it is.

Start out by finding the .png(an image format that supports transparency is required) you want to use as your new icon. Open your icon in Preview (the default app that OS X uses for images) and then choose “copy”. Now, [right-click]/[ctrl-click] the volume/device/app that you want to change and choose “Get Info”. Once that windows opens up you will see a little preview of the icon in the upper lefthand corner. Click on the icon preview, a small blue border should appear around the icon. Paste the image by pressing “apple-v”. Now assuming everything went as planned your item should have just updated itself and it should now be reflecting the new image. This process works for basically everything. If you have any questions E-Mail me(Lwestlie@gmail.com) or post  a question in the comments. Thanks!